More recent figures which are available for Finland (2) suggest that in that country over 36% of the cattle culled from dairy herds, whether of the Ayrshire or local breeds, are rejected for this same reason. Since much of the sterility in the bovine is functional rather than pathological, it is natural that the physiological aspects of a subject, so all-important to the dairy farmer, should continue to be studied in many research schools. For a clear and concise account of recent advances in this direction, reference should be made to a paper read by Hammond (3) at the Annual Congress of the National Veterinary Medical Association. The paper was very fully discussed by a number of prominent authorities and details of the discussion are published. Various factors, such as inadequate exercise, anatomical and functional hypertrophy of the mammary gland, hormone control and nutrition, were debated. For an excellent guide to present-day knowledge on the subject of nutrition as it affects fertility and reproduction, the reader should refer to an article by Crowther (4) in which the requirements of energy, protein, vitamins and minerals are lucidly discussed. The subject-matter is presented in a way which will be of much value to those interested in the practical aspects of animal husbandry. General articles have also appeared on the same subject by Campbell(5, 6), and by Mclntosh(7, 8). The latter deals particularly with diets deficient in phosphorus and vitamin A. The results of original work carried out during the past few years on the feeding of cattle in connexion with reproduction have been published recently by a number of authors. Smirnov-Ugrjumov & Laptev (9,10) report that liberal supplies of green foods and protein, particularly protein of animal origin, such as that contained in blood meal or skimmed milk, are most efficacious in increasing sexual activity and spermatogenesis in bulls. One reason for the value of green foods in this direction may be their content of vitamin C. The essential nature of this vitamin for fertility in the bull has been investigated by Phillips & Lardy(ii), who claim that lost fertility could frequently be restored by subcutaneous injection of ascorbic acid. They found that potent bull semen normally contains 1-5-3-5 mg. of this vitamin per 100 ml., and that values below 1 mg. and greater than i mg. were associated with very poor fertility and most unreliable breeding records. Owing to the importance of vitamin E for reproduction in some species it is natural that this factor should also be studied in connexion with bovine fertility. The view is generally held, however, that although vitamin E is probably an essential food factor for normal reproduction in farm animals, it is never likely to be of importance in actual practice, since it is so prevalent in much of the food normally fed on the farm. A paper by Underbjerg et al. (12) confirms this view in regard to the dairy goat. A general discussion on sterility as it is affected by such factors as climate, nutrition and endocrino...
